Don't you hate deals that have a ton of fine print? Thankfully, this one's pretty easy to follow: simply spend $100 on the PlayStation Network this month, and get a $20 credit back next month.
The promotion includes anything purchased with your wallet on the PlayStation Store, meaning you can buy games, movies, or TV shows and be eligible for the credit. And with many retail games hitting the PSN via Sony's "Day 1 Digital" promotion, there will be many opportunities to earn the $20 bonus.
For example, you can pick up Dishonored on day one via PSN, and be halfway to your spending goal. You could also pick up a PlayStation Plus subscription for $49.99 and be well on your way to unlocking the bonus. You can even sign up for DirecTV NFL Sunday Ticket, which will put you well above the requirement.
Once you reach the threshold, make sure you check your email. The voucher will be sent to the address associated with your PSN account, and won't be applied automatically. For some more spending ideas, you can check out the PlayStation.Blog.